Does your dishwasher leaves spots, film, or white residue on dishes? This article explains why and shows you how to solve these problems.

If a dishwasher washes poorly, a common cause is improper loading—dishes that block or impede the spray arms or prevent the soap dispenser from opening. On the other hand, if your dishwasher has chronic problems with good washing, the problem may not be your dishwasher. A good first step is to vary the amount of dishwasher detergent you’re using and try switching brands.

Man’s hand screwing a bolt beneath a dishwasher’s upper spray arm.
If your dishwasher does a poor job of cleaning dishes, make sure nothing is obstructing the spray arms. Also check the tension on the bolt at the hub of the upper spray arm to make sure the arm turns freely. ©Bacho / Shutterstock.com

Other possibilities: Your home’s water pressure may be too low, your water may be too hard, or the water temperature may not be hot enough.

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For other dishwasher repairs, see How to Repair Dishwasher Problems.

Dishwasher Does Not Clean Dishes

Problems with getting dishes clean usually have to do with the water pressure, the hardness of the water, or the ability of the spray arms to spin and spray.

 

Water Pressure Is Too Low

In order for your dishwasher to fill to the appropriate level, water pressure should be from 20 to 120 pounds per square inch. If you suspect that your water pressure may be low, turn off all faucets or other users of water (such as washing machines and sprinklers) and then put a half-gallon jug under the kitchen faucet.

Turn on the hot water full-blast. If the jug doesn’t fill within 14 seconds, your water pressure may be too low for proper dishwasher operation. Call your city water utility to discuss your options, or avoid drawing water elsewhere in the house or yard during dishwasher cycles.

 

Water Is Too Hard

The right amount of detergent to use depends on how large your load of dishes is and how hard your water is.

According to the United States Geological Survey (USGS) , water hardness is simply defined by “the amount of dissolved calcium and magnesium in the water”. Without defining the various degrees of severity, you can assume you have some level of “hardness” if your dishes are left with white spots after drying.

Hardness is measured in grains of minerals—the more grains per gallon you have, the more detergent you’ll need.

A color-coded U.S. map including calcium carbonate concentration in milligrams.
Hard water is very common in the United States, in some areas more than other. U.S. Geological Survey

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About Don Vandervort
Don Vandervort has developed his expertise for more than 30 years as a remodeler and builder, Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996. Read more about Don Vandervort